Technical Information

Belting Technical Information

Flat Wire Belt Materials

Galvanized low carbon steel (C1015)

Can be used in temperatures up to 500° Fahrenheit,
although usually limited to 350° as galvanizing will
flake off above this temperature

High carbon steel (C1050)

Used in the 350° to 800° Fahrenheit range for dry,
non-corrosive environments

Provides for higher strength at elevated temperatures

Has a greater resistance to abrasion than C1015

Type 304 stainless steel (T-304)

Standard material used in food processing industry

Highly resistant to most corrosive atmospheres

Can be used in temperatures up to 1100° Fahrenheit

Corrosive resistance may be lost at temperatures
above 800° Fahrenheit

Type 316L stainless steel (T-316L)

More resistant than T-304 to sulfuric, acetic, and
phosphoric acids

Stronger and offers greater resistance to corrosion
at higher temperatures

Type 201 stainless steel (T-201)

Highly resistant to most corrosive atmospheres

Can be used in temperatures up to 800° Fahrenheit

Extra strength due to slight work hardening

Belt Wrap

Keystone recommends that the maximum belt wrap on drive sprockets be limited
to 150o. Belt wrap of more than 150o could resist releasing from the sprocket and
continue a full revolution around the sprocket, damaging the belt. For tail sprockets,
the maximum wrap is not as critical, but should be limited to 180° or less.

Belt Identification Process

In order to identify a belt for replacement:

Measure the overall belt width, including the rods.

Count the number of openings across the width
of the belt.* This will always be an odd number.

Determine the belt gauge (standard duty or
heavy duty).
a) Determine the height of the strip by placing
the belt flat on a table and measuring from
the table to the top of the belt.
* A standard duty belt will measure 3/8" and a heavy duty belt will measure 1/2"OR
b) Measure the diameter of the connecting rod.* Standard duty rods can be 0.105" or 0.120"
and heavy duty rods are 0.192"

Measure the longitudinal pitch of the belt,
as shown.

Determine the selvage of the belt by visual
inspection.* This will be either clinched or welded, as shown.

Determine the belt material.* Because stainless steels are not magnetic,
a magnet can narrow the choice to either
a carbon or a stainless steel.
* Beyond this, material determination can be
done by application. For more information
about belt materials, see section above.

DRIVE TENSION CALCULATIONS FOR STRAIGHT RUNNING BELTS

(consult factory for TURN BELTS)

Important

Drive tension is used to determine the maximum load a belt can handle without premature fatigue and failure.

Consult Keystone for application assistance when approaching the maximum tension or for complex systems,
as well as for the maximum number of sprockets that can be used for a given belt width.

The fi gures for the maximum allowable tension are given for drum-driven applications. In order for the
belt to withstand these tensions with a sprocket-driven system, it is necessary to place a sprocket in
every drive opening.

Use the following equation for rough calculations. This calculation CANNOT be used for Key-Turn belts.

Calculate the drive tension per foot of belt width by dividing Td by the belt width (B).

If using the belt at an elevated temperature, multiply the maximum allowable tension per foot of width
(given in the conveyor specifi cations tables, pages 2-6), by a factor from the table below to get the
working tension at an elevated temperature.

Compare the calculated value from step 2 with the maximum allowable tension found in step 3.
The calculated value cannot exceed the maximum allowable tension.

ELEVATED TEMPERATURE (F) vs. STRENGTH

500

600

700

800

900

1000

1200

1400

Galvanized
Low Carbon

1.0

N/A

C1050
High Carbon

1.0

1.0

0.9

0.3

N/A

T-201
Stainless Steel

1.0

1.0

1.0

0.65

N/A

T-304
Stainless Steel

1.0

1.0

1.0

0.8

0.75

0.7

0.5

N/A

T-316
Stainless Steel

1.0

1.0

1.0

0.85

0.8

0.75

0.65

0.5

FRICTION FACTORS BETWEEN BELT & BELT SUPPORT

Belt Support

Friction Factor

Ball Bearing Rollers

0.10

Sleeve Bearing Rollers

0.15

Plastics Faced Slider Bed

0.20

Steel Slider Bed - Lubricated

0.30

Steel Slider Bed - Unlubricated

0.35

Sprocket Selection

To calculate the minimum number of drive sprockets for
a conveyor system:

Divide the drive tension (Td) by the maximum load
per sprocket (see table).

Divide the belt width (B), in inches, by 6 and add 1.

The larger of the two numbers is the minimum number of
sprockets needed.

Spacing of tail or idler sprockets should be between 6" and 9".

Never exceed a drive sprocket spacing of 6 inches, even for light loads.

Conveyor Belt

Maximum Pounds of Drive
Tension per Sprocket

Standard Duty Belts

1 Sprocket for every 70 lbs

Heavy Duty Belts

1 Sprocket for every 190 lbs

Decrease the maximum loading per sprocket for elevated
temperatures using the table above.

Sprocket Type

Maximum Belt Speed

Cast Sprockets

120 fpm

Machined Tooth Sprockets

250 fpm

Internal Welds

All welded selvage belts over 24 inches in width feature
the resistance welding of every other connector rod to the
flat strip on the 2nd opening in from each edge of the belt.
On True 1/2" x 1/2" mesh belts this weld is on every
3rd connector rod.

This provides for greater strength and eliminates belt shrinkage
under heavy loads without restricting flexibility of the belt.

Upon special request, belts 24" and under can be supplied
with internal welds.

COMPARISON OF FULL SCALE FLAT STRIP & ROD SIZES

Belt Tracking

The belt length to width ratio should be no less than 5:1 as tracking problems are more likely to occur with
wide belts which have a short length. Using alignment guides on the edges of a flat wire belt can cause
premature wear.

Since the majority of belting problems are alignment related, it is extremely important to have all shafts parallel
to each other and perpendicular to the conveyor bed. If a good alignment is not completed before using a flat
wire belt, longitudinal pitch can be distorted causing the belt to track to one side. Improper handling of the belt
before and during installation can also damage the belt creating alignment problems.

The best way to track a flat wire belt is to use several adjustable
support rolls located on the return side of the conveyor just before
the tail shaft. These rolls are skewed either forward or backward,
on a horizontal plane, to track the belt.

Belt Assembly

Belts are supplied with an additional connector rod for each 10 feet of belting. To splice sections, or to create
an endless belt, bring the two ends of the belt together and insert a connector rod. Standard duty, clinched selvage
connector rods are supplied with a preformed hook on one end and straight wire on the other. With pliers,
close this hook and form a similar hook on the opposite side. Welded selvage and heavy duty connector rods
are supplied with a button head weld on one end, and a thread nut on the other end. Tighten the nut and cut
off any excess rod. Rod end threads should be distorted to secure the nut.